1. Field of the Invention
The present invention relates to the art of printer, and more particularly, to an ink container to serve as an ink supply source of a printer and an ink supply source device incorporating such an ink container.
2. Description of the Prior Art
In a printer for automatically continuously printing a large number of prints such as a rotary type stencil printer, the ink consumed according to the progress of printing is continuously supplied from an ink container charged in the printer. As an ink container for this purpose there is known an ink container having a circular cylinder portion of a circular cross section, an end plate member mounted into the cylinder from one end thereof so as to be able to slide along the central axis of the cylinder like a free piston, and an annular end wall closing the other end of the cylinder except a central opening, and a nozzle connected to the central opening, the inside of the cylinder being initially filled with ink with the end plate positioned at the one end, wherein the end plate moves axially in the cylinder toward the other end as the ink in the cylinder is drawn out through the nozzle. (Japanese Patent Laid-open Publication 59-37162) When a printer is operated with an ink container of this construction, the resistance against the drawing out of the ink from the ink container remains always constant regardless of the amount of ink remaining in the container, whereby a large number of prints are available at a continuously stabilized density.
In the ink container of the above-mentioned construction, since the cylinder portion must operate not only as a wall means of a container for storing ink but also as a cylinder member for smoothly guiding the end plate member along the inside wall thereof like a free piston, the cylinder portion forming a principal portion of the ink container must have such a wall thickness that provides a high rigidity enough to operate as a cylinder for guiding a free piston therein, and therefore, a substantial amount of a material such as a synthetic resin or the like is required for the manufacture of the ink container, and further, the used ink container presents substantially the same outer configuration as that in its initial stage, although the end plate member is shifted to the deepest position of the cylinder to be close to the nozzle. Therefore, when the number of used ink containers increases according to the working hour of the printer, a difficulty should arise about the disposal of the used ink containers.
It is well known from old days to construct a fluid storing container to have a bellows construction. Particularly in Japanese Utility Model Application 60-94275 (Laid-open Publication 62-3438), there is proposed a container having a cylindrical portion of a bellows construction having a closed one end and another end having an opening, and a nozzle connected to the opening. Further, it is shown in Japanese Patent Laid-open Publication 6-199349 to construct a bellows type ink container for a printer such that an inner cylinder of a bellows construction projects from an end of a main cylinder portion toward the inside thereof, such that the amount of ink which remains in the ink container after the end of possible discharge of ink therefrom is decreased.
Further, in Japanese Patent Application 9-39712, there is proposed an ink container comprising a vessel constructed from a bag made of a flexible sheet and collapsible to be flat, a nozzle connected to one end of the vessel, and a cylinder member made of a relatively hard sheet material collapsible to be flat, the cylinder member covering a half or nearly the whole length of the bag, wherein the container is inflated to a cylindrical configuration by ink being charged therein.
However, when such a container having a bellows construction or made of a flexible sheet is constructed to have a very thin wall thickness, the cylindrical container formed by the inflation thereof by a charge of ink therein is difficult for seizure by fingers as it readily flattens by the application of pressing forces by the fingers, so as to release the pressing forces, thereby nullifying the seizing function by the fingers. When the container has a simple cylindrical configuration with no bellows, an effective seizure by fingers is more difficult than in a container having bellows. When it is only needed that the container is hung up, a cap mounted to the nozzle may be grasped by tips of fingers. However, when the container filled with ink is charged into a printer, the cap must be removed. In order to remove the cap tightly clamped not to cause a leakage of ink, the cylindrical portion of the container must be firmly held. If a firm holding is not available, it will be very difficult to remove the cap. Further, if the cap is removed by clamping the flexible cylinder portion, at a moment when the cap was removed, the ink will be inadvertently ejected out from the container.